Why are some of my pictures getting grey bars on them when I put them on the computer?

Its just a glitch on your computer, probably some graphics related issue. Try updating your graphics drivers. I've seen many of these weird glitches on my old pc, that pictures make spots and stuff that arent really there. What i'm saying is that your pictures are fine, don't worry. Try uploading them on a different computer and you'll see they work. If they work on the camera they are fine.